Pen cap



FIG. 1 is a bottom, front and right-side perspective view of a pen cap in accordance with the invention;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side elevational view thereof, the right side being a mirror image; and,

FIG. 4 is a rear side elevational view thereof. 

The ornamental design for a pen cap, as shown. 